This invention relates to an optically pumped continuous wave (C.W.) gas laser and more particularly to optically pumping Hg--N.sub.2 with a resonance lamp containing Hg therein in order to produce a laser output of 546.1 nm.
Heretofore all known C.W. visible gas laser systems have been excited by an electrical discharge. In such laser systems, an electric discharge produces a plasma in the gas which serves as the active laser medium. In order to establish a population inversion in such C.W. gas laser systems, the lower laser level must be quenched at a rapid rate. The atomic levels closest to the ground state cannot do so radiatively either because of metastability or because of radiation trapping. Consequently, all known previous C.W. visible gas lasers have utilized very high lying energy levels for the laser transition which is responsible for the low efficiency of such systems. In order to produce laser systems operating on low lying energy levels, thereby producing high quantum efficiency, one must resort to quenching the lower laser level through collisions of the second kind. However, for the latter to be effective, the pressure of the quenching gas generally would have to be much greater than the pressure of the active atomic species. This condition poses two problems for the practical application of collisional quenching in electric discharge systems. First, the large concentration of the quenching gas will absorb much of the electron energy in the discharge, leaving little for the excitation of the active species. Furthermore, the high total pressure of the system may actually prevent the gas from breaking down to become a glow discharge. For the above reasons, it is generally believed that the C.W. visible lasers with electric discharge excitation will not produce a high efficiency output.
A system such as set forth above has been described in "Mercury-Vapor Lasers", by V.M. Klement'ev and M.V. Solov'ev, Journal of Applied Spectroscopy, Vol. 18, pp. 29-37, January 1973.